Actuators with torsion arms facilitating preselection in crossbar switches

ABSTRACT

In typical crossbar switches, selection operators move flexible fingers to restricted areas within openings of selected operate cards, and subsequent operation of hold actuators against the fingers operate the selected cards. According to this disclosure, the ends of the flexible fingers that are to be engaged by operated selection operators are bent to function as levers that are rotated quite readily as a result of the twist of the long portions of the flexible fingers. The torsional spring characteristic provided by the levers permits the selection operators to operate fully during preselection without requiring much more than normal operating force.

United States Patent Symes [151 3,660,627 [451 May 2,1972

[54] ACTUATORS WITH TORSION ARMS I FACILITATING PRESELECTION IN CROSSBAR SWITCHES 211 App]. No.2 76,839

52 u.s.c|..- .L ..200/1'75,335 112 51 Int.Cl ..II0lh67/26,I-l01h63/33 [58] Field oiSearch ..200/l75, 176, 177, 178, 179, 7

[56] Reierences Cited UNITED STATES PATENTS De Smet .;200/175 x 3,445,795 5/1969 Holtfreteretal. ..335/ll2 2,955,168 10/1960 Schacht ...335/l1l 3,474,207 10/1969 De Smet ..200/l75 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Att0rney--K. Mullerheim, B. E. Franz and David W. H eid [57] ABSTRACT In typical crossbar switches, selection operators move flexible fingers to restricted. areas within openings of selected operate cards, and subsequent operation of hold actuators against the fingers operate the selected cards. According to this disclosure, the ends of the flexible fingers that are to be engaged by operated selection operators are bent to function as levers that are rotated quite readily as a result of the twist of the long portions of the flexible fingers. The torsional spring characteristic provided by the levers permits the selection operators to operate fully during preselection without requiring much more than normal operating force.

4 Claims, 2 Drawing Figures PATENTEDHAY 2 I972 NN w ATTORNEY s cxoaouuo or THE INVENTION -This invention relates to electromagnetically operated switches of the crossbar type and particularly toan improve- ,men tin th ei r actuators for preselecting crosspoints.

e ssbars ch to which the present improvement isap- .plic rs rrbedin U.S. Pat. No. 3,445,795 issued to R. P. flOlglQbe l' Qt von May 20, 1969. Each crosspoint comprises a plus ity of contacts extending through an operate card. The card for each f he crosspoints is urged to an unoperate posiio b a so 7 and his moved t an ope a Po y cooperation a legion actuator, a flexible finger, and a h d r, Each flexible finger passes. through an opening ctive card the. opening havinga shape that deteramount t free movement of the finger in a longitu- I, direction Oi'the card according to the lateral placement of the finger. That portion of an opening that allows longituoia finger. without moving the card is said to area,'and that portion that does not allow ent is a restricted area. The flexible fingers ally iased toward the unrestricted areas, and until are moved tova restricted area, movement of the fingers by op ration o e hold ac u does not e c rds from their unoperate positions. When the flexz indiv dually selected first by operation of the swa m the ar move la ly into the is t stsa s a and ubsequen pe at o s of their hold tuators against the flexible springsicausethem to move the i l n tud nal y t t e ope Position After is held, operated as. long as itshold l fi il gdi r s .at.d,-. Y y, a seleetign actuator is. nQt Operated to. make anew on. unt l: s its: the sso a sd o di c uators andzthe flexible fingers H trolled therebyhave been retumed. to.normal, a a. ist qss sslscted cro p in s. een relea e However, faster eration' achi eyedinpresent,switching-systems. was. a ti n h sss ec hn au ssa s s io actuator t ope ted, before an associatedg hold actuator has had; time: to. re rn, .itsnormahposition. While the-holdactuator. is still: in its operate osition, it,is pressingagainstunselectedfingersv whels r h marartofi hck r st c dareathat ppositto.that;Wherq hefingersare.normally-located. Themovementof these- 'gersis therefore restricted; laterally as; well aslon- R Q ii; the hh oldj actuator. has; returned from. its on. The flexiblej fingersv of; crosspoints; other stilloperated froma previouslselection, that'are' hehold actuator.andtthe-selectimactuator must rsely; anabnormalamount to permit full lateral qpsretlqs f: e. ssoc ate ele tion, ct ato The fo e pr ss s i q t. is pre ented 3 unless, h c u to s n: pr i greaterQ mce hwth t qrma lyrsquir dr SUMMARY. E HEINMENTIQN.

Crossbar. switches aecording t this invention, have an; improved i selection opei'fltors and flexiblefingers ators Onlymoderateforce is required to ators because the. flexiblefingers the selection, operatorsot. the selecors. press during, ,their,operation.- The. selection bthiS t stiiaight members attached. to. selection, actuator 65' bars tocontaet levers at adi efrornthe axes of the respective l ile xible,fit gers. As, the selection operators are ,moved heavy load on the magnets thatoperate the selection operators. Asa hold actuator returns to its normal position, the

selectedflexible finger that is in a constrained position, moves alongthe curved side of the opening to a select position where the torsional strain caused by pressureof the selection operator is small.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an oblique view of fragmentary select and hold actuators of a crossbar switch to show-preselection according to this invention; and t FIG. 2 is a view of the upper right actuators of FIG. 1 as they appear for an instant while the hold actuator is releasing during preselection.

DESCRIPTION OF THE PREFERRED EMBODIMENT the flexible fingers have been shaped according tothis inven tion to provide tion magnets.

Each of the crosspoints 11-18 has cards 24-31 respectively to operate contacts 19. to engage fixed contacts thatare not shown. A crosspoint to be operated is selected by a selection actuator, and is then operated by a hold actuator assembly. For example, any of the crosspoints 11-14 after being selected can be operated by the operation of the hold bar 20 to move their respective cards 24-27, and likewise any of the crosspoints 15-18 after being selected can be operated byoperationof the hold bar 21. which oneof the cards 24-31 is to be operated by operationof aholdbar is determined by'the position of a respective flexible finger that passes through. an opening in'the card. Each. of the openings located at one end of the card has in generala triangular shape with a straight side in the longitudinal'direction-and an adjacent straight side in the direction across the card.- The third side is curved inward toward the preselection without unduly loading the selecright angle between the straight sides'so that the overall shape resembles a sharply. curved'boomerang. The end of the curve withoutrequiringuseofexcessive-force 6r) ssinstths l vers; hsflsxih a nsst er tq allow the levers torotate. The flexibl fingers can usually be quite easily througlrrtheir. cards, the .flexible n ofitheir levers withoutplacing a side. that joins the adjacent lateral side is substantially parallel to the. lateral sideand is offset slightly therefrom'to receive the respective flexible finger during selection of the card for operation. I

In apreferred embodiment, the flexible fingers for two adjacent cards are joined in'a bight, and the bight is fixed to a mounting button; For example, the fingers 32 and 33 are joined by a bight 40 that is used to mount the fingers on a fixed button 41. The free end of each of the fingers 32-39 has a portion 42-49 respectively bent at right angles to the rest of the finger. The bent portions-of each of the joined pair of fingers are parallel to the longitudinaldirection of the cards and are spaced apart slightlyto receive aselection operator 50 53 wardly quite easily by its selection operator from its normal position-to its operate position. During normal operation, the force required tov move thefinger laterally is not enough to "cause. much twist of the finger, but during preselection as described below, the-fingers are constrained much closer to the selection operator, and with a moderate additional force, the-flexiblefinger twists to prevent excessive resistance to full operation of the selection operator.

In FIG. 1, the positions of the flexible fingers for the different crosspoints are shown-according to the operation of their respective selection actuators and hold actuators. For the crosspoints 13 and 14, the selection bar 56, the hold bar 20, and the flexible fingers 34 and 35 are shown in their normal positions. 'At the crosspoint 12, the selection bar 57 has been rotated away from the flexible finger 33 of the crosspoint 12 to move its operator 50 against the adjacent flexible finger 32. Therefore, the finger 33 is also in its normal position, but the finger 32 has been moved laterally within its opening in the card 24 to the operate position where it is constrained longitudinally in the card. As described above, the force required to move the finger freely in its opening is too small to cause much twist in the finger 32. Since the hold bar is unoperated, the positioning of the finger 32 has no effect on the position of the card 24.

The hold bar 21 common to the crosspoints 28-31 is shown operated. Since neither of the flexible fingers 38 and 39 of the crosspoints 17 and 18 has been moved laterally from its normal position, the hold bar 21 has moved both of them freely longitudinally within the openings through which they extend while the cards 30 and 31 remain in their normal positions.

To illustrate the advantage of utilizing the torsional spring characteristic of the flexible finger 36, the positions of the crosspoints 15 and 16 are shown when the hold bar 21 is still operated from a previous selection of the crosspoint 16, and the selection bar 57 is operated to preselect the crosspoint 15. The hold bar 21 is to be returned to normal instantly and then to be operated again immediately for operating the selected crosspoint l5. i

The finger 37 of the crosspoint 16 is still retained in the restricted area of its opening in the card 29 by the hold bar 21, and the card 29 is still in its operate position. As the hold bar 21 returns to normal, the flexible finger 37 returns by its own spring force to its normal position in the right angle of its opening.

. The rotation of the bent portion 46 of the flexible finger 36 permits operation of the crosspoint 15. Since the hold bar 21 has not had time to return to normal from its previous operation, the flexible finger 36 is retained in the area between its longitudinal side and its curved side 58. While the finger 36 is retained and the selection bar 57 is operated to force the operator 51 against the bent portion 46 of the finger, the long portion of the finger offers much greater resistance than usual to bending because it is constrained by the card at a point near the selection operator. As the force becomes somewhat greater than that required to bend a normally positioned flexible finger, the bent portion or lever 46 rotates to relieve the force on the actuator (lipt shown) that operates the select bar 57.

In FIG. 2, the position of the flexible finger 36 within its of the finger 36 is restricted in the card 28. As the finger travels to its normal operate position, the bent portion 46 rotates until it is substantially parallel with the longitudinal direction of the card 28. The position of the finger 36 of the crosspoint 15 therefore becomes similar to thatshown for the finger 32 of the crosspoint 11. The crosspoint 16 is now released, and the hold bar 21 operates again to operate the crosspoint 15 to the position shown for the formerly operated crosspoint 16 in FIG. 1.

lclaim:

1. In a crossbar switch assembly of the type'having a plurality of actuator cards, a plurality of movable crosspoint contacts extending through each of said cards, means biasing said cards individually to an unoperated position, said cards being translatable to an operated position to actuate respective ones of said contacts, each of said cards having an opening with an unrestricted area and a restricted area, a resilient fin er extendmg substantially perpendicularly through eac of said openings, each of said fingers being biased toward said unrestricted area, a plurality of rigid selection fingers each selectively operable to move a corresponding one of said resilient fingers in opposition to its bias to a restricted area of the corresponding card, and a hold actuator operable to impart a movement to said resilient fingers such as to cause only the ones of said actuator cards having the resilient finger in the restricted area to be translated from an unoperated to an operated position;

the improvement comprising a bent portion forming a lever at the end of each said resilientfinger, each of said selection fingers being arranged to engage the ,bent portion of the corresponding resilient'finger at a point to provide torsional leverage on said resilient finger, and the twisting of said resilient finger allowing movement of the selection finger with a moderate amount of force when said resilient finger is positioned in said unrestricted area of said actuator card during preselect operation.

'2. The improvement in a crossbar switch assembly as claimed in claim 1 wherein said opening in each of said actuator cards is shaped like a sharply curved boomerang, said unrestricted area being one arm of said opening extending lon- 'gitudinally along said actuator card to permit freedom of movement of the corresponding one of said resilient fingers in the longitudinal direction of said card, and said restricted area being the other arm of said opening extending across said actuator card to prevent free longitudinal movement of the corresponding resilient finger therein.

3. The improvement in a crossbar switch assembly as claimed in claim 1 wherein said resilient fingers are joined in pairs by a bight at one end of each pair, and said bent portion of each of said fingers is bent at a right angle at the opposite end thereof.

4. The improvement in a crossbar switch assembly as claimed in claim 1 wherein said resilient finger is substantially L-shaped, and the corresponding selection finger engages the base of said L'to provide torsional leverage on said resilient finger. 

1. In a crossbar switch assembly of the type having a plurality of actuator cards, a plurality of movable crosspoint contacts extending through each of said cards, means biasing said cards individually to an unoperated position, said cards being translatable to an operated position to actuate respective ones of said contacts, each of said cards having an opening with an unrestricted area and a restricted area, a resilient finger extending substantially perpendicularly through each of said openings, each of said fingers being biased toward said unrestricted area, a plurality of rigid selection fingers each selectively operable to move a corresponding one of said resilient fingers in opposition to its bias to a restricted area of the corresponding card, and a hold actuator operable to impart a movement to said resilient fingers such as to cause only the ones of said actuator cards having the resilient finger in the restricted area to be translated from an unoperated to an operated position; the improvement comprising a bent portion forming a lever at the end of each said resilient finger, each of said selection fingers being arranged to engage the bent portion of the corresponding resilient finger at a point to provide torsional leverage on said resilient finger, and the twisting of said resilient finger allowing movement of the selection finger with a moderate amount of force when said resilient finger is positioned in said unrestricted area of said actuator card during preselect operation.
 2. The improvement in a crossbar switch assembly as claimed in claim 1 wherein said opening in each of said actuator cards is shaped like a sharply curved boomerang, said unrestricted area being one arm of said opening extending longitudinally along said actuator card to permit freedom of movement of the corresponding one of said resilient fingers in the longitudinal direction of said card, and said restricted area being the other arm of said opening extending across said actuator card to prevent free longitudinal movement of the corresponding resilient finger therein.
 3. The improvement in a crossbar switch assembly as claimed in claim 1 wherein said resilient fingers are joined in pairs by a bight at one end of each pair, and said bent portion of each of said fingers is bent at a right angle at the opposite end thereof.
 4. The improvement in a crossbar switch assembly as claimed in claim 1 wherein said resilient finger is substantially L-shaped, and the corresponding selection finger engages the base of said L to provide torsional leverage on said resilient finger. 